Re-instantiating environment within a loop

[zubair-irshad]

I am re-instantiating TurtlebotNavigateSpeedControlEnv in a for loop. In the headless, display_ui =false mode, I get the following error at finish loading shaders:

terminate called after throwing an instance of 'zmq::error_t' what(): Address already in use

It seems like the environment is not terminating correctly before re-instantiating. Is there a way to terminate the environment after a loop is finished?

[fxia22]

Looks like it's similar to #22